It is known from U.S. Pat. No. 5,084,490 and U.S. Pat. No. 5,141,970 that cationically cured propenyloxystyrene monomers have outstanding thermal and mechanical properties. The monomers undergo a 2-stage curing process involving an initial acid catalyzed addition polymerization or copolymerization of the styrene group (A-stage), followed by a heat-triggered post-curing reaction of the propenyloxyphenyl group (B-stage). During the post curing reaction, the A-stage polymer rearranges to form a reactive phenolic polymer, which spontaneously reacts with the propenyloxy group via an electrophilic substitution reaction. This results in the formation of a highly crosslinked polymer that exhibits a high decomposition temperature (T.sub.d &gt;400.degree. C., TGA), a high glass transition (T.sub.g &gt;300.degree. C., DMA) and good adhesion.
U.S. Pat. No. 5,369,200, Schadeli et al. (1994), describes terpolymers of two different maleimide monomers and an olefinically unsaturated phenyl ether monomer in which the phenyl ether is defined by an acid cleavable group --OR.sub.2 linked to a phenyl ring. Examples of such monomers in this reference include a terpolymer of 4-(2-tetrahydropyranyloxy)benzyl methacrylate, N-hydroxymethylmaleimide and N-(acetoxymethyl)maleimide. The terpolymers are used as positive resists with acid generating photocatalysts and therefore it is imperative that the --OR.sub.2 group be selected to be acid cleavable.
U.S. Pat. No. 5,211,877, Andrejewski et al, (1993) and U.S. Pat. No. 5,641,850 (Stoher et al) describe liquid-crystalline polyorganosiloxanes containing (meth)acryloxy groups. Also described are the monomers 4-(prop-2-ene-1-oxy)benzoic acid 4-methacryloxyphenyl ester and 4-(prop-2-ene-1-oxy)benzoic acid 4-(4-methacryloxybiphenyl)ester,
U.S. Pat. No. 4,468,524, Zahir and U.S. Pat. No. 4,387,204, Zahir describe alkenylphenyl substituted acrylates or methacrylates and crosslinkable monomer compositions employing same.
Anaerobically curable compositions are a well known class of curable (meth)acrylate monomers composition. The compositions typically include polyfunctional monomers such as polyethylene glycol dimethacrylate (PEGMA), although some systems based on mono(meth)acrylates are known. The compositions also include a free radical catalyst system which is stabilized by atmospheric oxygen. The catalyst system usually include a hydroperoxide catalyst, typically cumene hydroperoxide, and at least one accelerator. Benzenesulfimide (saccharin) is a typical accelerator. Other common accelerators include acetyl phenyl hydrazine and dimethyl-para-toluidene. Deprivation of oxygen characteristically initiates cure (although initiation frequently also requires an additional condition to be simultaneously met, such as the provision of a source of metal ions or of heat). Anaerobically curable compositions are widely used as thread lockers, pipe joint sealants, gasketing agents, adhesives and as impregnation resins. To achieve a storage stability which is balanced based on access to atmospheric oxygen, other stabilizers are conventionally included in the composition.
It would be desirable to have anaerobically curable compositions which have improved high temperature resistance, especially a heat resistance capability comparable to the heat resistance of the B-staged cationically cured propenyloxystyrene monomer compositions described in U.S. Pat. No. 5,084,490 and U.S. Pat. No. 5,141,970.